Elsewhere on the Army installation in Harford County, soldiers train on radio jammers intended to render enemy remote controls useless. At still another location, inventors work on hand-held test kits that will enable troops to identify chemicals used by bomb makers.

All of the activity is aimed at stopping the signature weapon of the enemy in Afghanistan and Iraq: the improvised explosive device, the IED, which has been responsible for more than half the American combat deaths over the past decade and many of the brain injuries and amputations.

Aberdeen Proving Ground has emerged as a significant contributor to a priority effort across the military to protect troops against the roadside bombs and other homemade explosives that have been called the "artillery of the future."

Military officials reported a record number of IED attacks in Afghanistan in 2011, the most recent year for which statistics are available. The weapon has been adopted by insurgents and terror groups in Africa, Asia, Latin America and beyond. Analysts expect their use to increase.

Dr. Scott E. Schoenfeld, a scientist with the Army Research Laboratory at APG, calls it a "broad-front battle."

His laboratory has worked to develop more effective armor for military vehicles, which has been credited with saving limbs and lives in Iraq and Afghanistan.

The signal-jamming Duke system, fielded by a team at the base, is credited with reducing casualties from bombs triggered by cellphones and other radio devices. Other efforts aim at developing sensors to find bombs and remote-control devices and to detect the common fertilizers and oxidizers used to make explosives.

"They're paddling as fast as they can," said explosives expert and author James B. Crippin, who provides specialized training in IEDs to law enforcement, the military and foreign governments. "It's the big thing right now, and there's a reason why it's the big thing. It's because nobody can come up with a good, all-around answer."

At the Rodman Materials Research Building — seven acres under one roof — Schoenfeld reviews a video of the test bomb exploding. The device is based on IEDs encountered by coalition forces in the field. Details of those weapons are relayed to APG by the troops who encounter them, by intelligence officers and by Army Research Laboratory scientists who travel voluntarily to the battlefield to collect information.

Schoenfeld, who trained as an earthquake engineer, studies the performance of materials under stress. The purpose of the test blast, he says, is to better understand the interaction between the shrapnel — "that lethal deadly fragment set" — and its target.

A high-energy X-ray machine produces pictures called radiographs of the shrapnel spray, which researchers will use to improve their computer simulations of IED explosions. The "long-term science mission," Schoenfeld says, is designing new, efficient materials from which to make armor to protect the troops in the field.

It's a mission that gained urgency during the Iraq war, when the IED emerged as the most effective weapon of the insurgency. Underequipped U.S. troops began to improvise their own armor — hanging Kevlar vests outside Humvees or incorporating bullet-resistant windshield glass or sandbags.

Schoenfeld, the force protection manager for the Army Research Laboratory, says some of their measures were effective but others put soldiers in greater danger.

"Overmatched armor is a very dangerous thing," he said. "What happens is that bullet breaks up, the metal from the armor breaks up and essentially generates a lethal spray of fragments and devices. You could actually be better off if you had no armor, because the bullet would pass right by you."

A common misconception, Schoenfeld says, is that armor is a large piece of metal intended to stop bullets or shrapnel. In fact, he says, armor can be more effective if it is deflecting projectiles or breaking them.

Researchers at Aberdeen helped to develop the armor for the Mine Resistant Ambush Protected vehicle program, known as MRAP. Many of the vehicles employ V-shaped hulls to steer shrapnel away from the occupants. The MRAP program was credited with drastically reducing injuries and fatalities in IED attacks, but Schoenfeld says the battle is far from over.

"It's an ongoing cycle," he said. "No matter what we do, someone's going to be trying to find a counter to that."

Still, he said, each successful U.S. measure against IEDs "stresses the enemy."

"They've got to dig a bigger hole. They've got to get more [explosives]. And that makes their job harder, stresses their supply chain, their supply chain management, makes them more exposed."

Lt. Col. Bruce Ryba says radio jamming of remote-detonated IEDs has had a similar effect. Ryba heads the team that manages the Duke system — essentially, a metal box used by troops to send out signals that block cellphones and other devices insurgents use to trigger bombs.

"[Insurgents] used to have what they call a 'drop and pop,'" he said. "In five seconds, they can pull a vehicle up, stop, drop [a bomb] on the side of the road and be gone. And then the guy can stand off with radio control. Now they're forced ... to get out there and run wire. They're forced to dig holes to put the pressure plates in. So, it does expose them more where our intel assets can follow them, watch them, see them — prevent."

In 2007, Ryba says, remote-control IEDs caused 85 percent of the IED casualties. Today that has fallen to 12 percent.

Maj. Sarah Forster says she saw the effectiveness of the Duke system in Iraq. When she first deployed in 2004 as an engineer platoon leader, the enemy used remote-control IEDs, she said, "but we really had no measures to counter."

She returned in 2007 to help deploy the Duke system.

"You have just that extra boost of confidence in knowing that you have that equipment that's going to protect you," she said. "It just makes a huge difference and allows you to focus on the mission."

Crippin, the explosives expert, sees no end to the fight against IEDs.

"The bad guys are able to react quicker to what you do, and it takes longer to react to the changes that they do," Crippin said.

All of the military efforts against IEDs are "going to be successful — up to a point," he said. "But IEDs can be so unique and so definitive, you can't guard against all of them all of the time every time. No matter what you do, somebody will come up with a way to get around what you've done, and then you get to go back to start from square one."

Michael Crapanzano, deputy director of the software engineering center at the Army Communications-Electronics Command, says the Army's efforts against IEDs are evolving from what has been a wartime response to a battlefield threat to a campaign against a weapon that appears to be here to stay.

"Whatever we learn from this last effort, we want to prepare the Army to utilize these same devices potentially for any effort that the Army might [find] itself in in the next 10, 20 years," he said. "There are a lot of great capabilities here at APG now that we want to leverage off of and bring to another level."